Using a corpus to investigate empirically grammatical phenomena prior to writing grammatical rules or constraints for a disambiguating tagger is important. The paper shows how even case distinctions on pronouns are used more diversely than is usually assumed. Both in English and Norwegian nominative pronouns are used in more positions than the expected Subject one. Although the other uses are statistically less frequent, they may be important to the users of the resulting tagged corpus – who are often theoretical linguists. A tagger should therefore tag correctly also the more infrequent constructions. The paper shows how this can be done in a Constraint Grammar type tagger.